“And so we say goodbye to two gentlemen. Two, very, gentle, men.” Those words, or something similar, were the final lines of narration of the Laurel and Hardy compilation movie that was a TV Christmas perennial when I was a boy. They weren't the cleverest, they weren't the wittiest but they were the funniest. They were primarily exponents of comedy's basest matter, slapstick, and it was often cruel and petty and mean and violent, but the laughter they produced was incredibly pure and cleansing. It was the best medicine the 20th century had to offer.

Which makes any kind of biopic of two such saintly figures a tricky proposition. Biopics usually demand conflict and revelation and, accustomed as we now are to tears-of-the-clown disclosures about comedy giants, I would be grabbing my pitchfork and burning down houses of anyone suggesting a dark side to these two. Jeff Pope's script focuses on the pair in the 50s, old and ill and out of fashion (supplanted by Abbot and Costello) and doing a tour of British theatres for Bernard Delfont (Jones) in the hope of generating interest in a new Robin Hood film. And there is a moment of rancour between them, but only to precipitate a making up. Mostly this is a vision of contentment, an arranged marriage – the pair were put together in the silent era by Hal Roach (Huston) – that has made it through to its pearl anniversary.

The film views their life as an ongoing piece of performance art. Their onscreen personas by this time are so well practised they have largely become their way of dealing with day-to-day life. Though there are some decent supporting roles for Henderson and Ariande as the wives, the film is primarily a showcase for Coogan and Reilly's superb performances in the title roles. As impersonations, they are just about flawless (the prosthetics to give Reilly Hardy's chubby chops are seamless) and there is something very touching about seeing two such gifted comedy performers suppress their usual skills to revive these two legendary figures. My only quibble is neither of them looks as old or infirm as the pair does in pictures from the era.

It must be the best part of half a century since I first saw a Laurel and Hardy film and though there are many childhood things I retain a fondness for, I can't think of anything else from childhood that I can watch as a middle-aged man and enjoy as completely, and in exactly the same way, now as I did then. Everything else tos and fros in my affections but they are a constant. For me this was moving and overwhelming in the way A Star Is Born was everybody else. It is though a film for the converted. I'd be happy to be proved wrong but I suspect that this won't find a new generation waiting to be introduced to their comedy magic. Probably it won't penetrate beyond the coterie of middle-aged men (and it is almost exclusively men) that adore them. I think this is partly because although the film is consistently funny, the scenes of Laurel and Hardy performing on stage aren't, not particularly. Immaculate and blissful as Coogan and Reilly are, when they re-enact the pratfalls and misunderstandings, it seems mechanical. Which is probably the finest tribute you could pay to their unique gifts – only Laurel and Hardy can really make Laurel and Hardy funny.